ATAN(3) Linux Programmer's Manual ATAN(3)NAME
atan, atanf, atanl - arc tangent function
SYNOPSIS
#include <math.h>
double atan(double x);
float atanf(float x);
long double atanl( long double x);
Link with -lm.
DESCRIPTION
The atan() function calculates the arc tangent of x; that is the value
whose tangent is x.
RETURN VALUE
The atan() function returns the arc tangent in radians and the value is
mathematically defined to be between -PI/2 and PI/2 (inclusive).
CONFORMING TO
SVr4, POSIX.1-2001, 4.3BSD, C89. The float and long double variants
are C99 requirements.
SEE ALSOacos(3), asin(3), atan2(3), carg(3), catan(3), cos(3), sin(3), tan(3)
2002-07-27 ATAN(3)